Recently, liquid crystal display (LCD) technology has been developed rapidly, great progress has been made in both the size of a screen and the display quality, and LCDs, due to the characteristics of small size, low power consumption, no radiation and the like, have occupied a dominant role in the field of flat panel display.
A touch screen is an important device that integrates input and output terminals. In recent years, with the arising of a series of products such as small and light handheld equipments, the demand of markets for touch screens is increased sharply.
FIG. 1 is a structural schematic diagram of a touch screen in the prior art. The touch screen in the prior art is a voltage sensing touch screen and includes an array substrate and a color filter substrate. As shown in FIG. 1, the array substrate includes gate lines 1, data lines 2, and a set of touch scan lines 3, touch sensing lines 4 and light sensing units 5 which independently realizes a touch function, wherein each light sensing unit 5 includes two independent light sensing structures, to which the touch scan lines 3 and the touch sensing lines 4 is connected, respectively. When the touch screen is touched, the two light sensing structures send electric signals to the corresponding touch scan line 3 and touch sensing line 4, respectively. The coordinates of a touch point may be calculated after a control unit of the touch screen receives the electric signals from the touch scan line 3 and the touch sensing line 4, so that positioning of the touch point is realized.
When the touch screen carries out displaying, light is emitted from a backlight plate, but not all light can pass through a panel, e.g. at positions corresponding to signal lines (data lines 1, gate lines 2, touch scan lines 3 and touch sensing lines 4), thin film transistors (TFTs), storage capacitors and the like. It is not completely light-transmissive at these positions, and light passing these positions is not controlled by voltage, so that gray scales cannot be displayed accurately, and all these positions need to be shielded by a black matrix so as not to interfere with other light-transmissive areas.
Both the touch scan lines 3 and the touch sensing lines 4 are arranged on an array substrate with gate lines and data lines formed thereon in the prior art, which inevitably results in enlarged area of the black matrix on the color filter substrate and reduced area of light-transmissive areas of pixel units, and thus the aperture ratio of the pixel units decreases.
Moreover, by arranging the touch scan lines 3 and the touch sensing lines 4 on the array substrate, lines on the array substrate are excessive, the difficulty in manufacturing the touch screen is increased and defective productions are also increased.